Burn-in carrier and semiconductor die assembly

ABSTRACT

A method of using adhesive tape to temporarily retain a die being temporarily held in a fixture during testing and burn-in. The method of the present invention uses a die cut piece of adhesively coated tape to hold a die in a test and burn-in fixture. Upon subsequent heating of the tape beyond the normal operating range of the adhesive coating on the tape, the die is removed from the tape, the tape is removed from the test and burn-in fixture, and the remaining adhesive, if any, is removed from the test and burn-in fixture.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of application Ser. No.09/488,210, filed Jan. 19, 2000, pending, which is a continuation ofapplication Ser. No. 08/994,005, filed Dec. 18, 1997, now U.S. Pat. No.6,064,221, issued May 16, 2000, which is a divisional of applicationSer. No. 08/581,905, filed Jan. 2, 1996, pending.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention relates to a method of temporarily securing a dieto a burn-in carrier for the purpose of burn-in and testing of the die.More specifically, this invention relates to a method of temporarilysecuring a die to a burn-in carrier through the use of adhesive tape forthe purpose of burn-in and testing of the die.

[0004] 2. State of the Art

[0005] Integrated circuit memory devices, such as dynamic random accessmemories (DRAMS) and static random access memories (SRAMS) are testedduring manufacture and often prior to use. Such testing is for thepurpose of insuring that only known good dies are subsequently used.

[0006] One of the test procedures which is used to determine theviability of integrated semiconductor circuits is a burn-in procedure.The burn-in test is intended to stress the electrical interconnection ofthe die and drive any contaminants in the body of the die into theactive circuitry, thus causing failure. This test is based on dataindicating that dice that are prone to these types of failures willactually malfunction in the early part of their lifetime. By conductingburn-in tests, the early failures of the dice are detected and onlyknown good dice are subsequently used in applications.

[0007] In the testing of a die prior to encapsulation, temporaryelectrical connection must be effected between the die and a testfixture. This is typically done by connecting the test fixture to thedie using the bond pads of the die through the use of wire bonds or tapeautomated bonding. As is evident, the testing of an unpackaged or baredie requires a significant amount of handling. Since the test packagemust be separated from the die, the temporary packaging may be morecomplicated than either standard discrete packaging or multichip modulepackaging. The package must be compatible with any desired test andburn-in procedures without damaging the die at the bond pads orelsewhere during any such test or burn-in procedure.

[0008] In U.S. Pat. No. 4,899,107, a reusable burn-in test fixture fordiscrete tape automated bonding (TAB) a die is disclosed. The fixtureconsists of two halves, one of which is a die cavity plate for receivingsemiconductor dies as the units under test and the other halfestablishes electrical contact with the dice and with the burn-in oven.The dice are held in position within the carrier by being resilientlymounted therein.

[0009] In U.S. Pat. No. 5,408,190, a reusable burn-in test fixture fordiscrete dice is disclosed. The reusable burn-in test fixture comprisestwo halves, the first half containing a cavity in which a die isinserted. As disclosed, a precured RTV silicone backing strip is used toretain a die in a face-up position in the carrier. The precured RTVstrip, commonly known as a “gel pack”, exhibits a static charge andcoefficient of friction sufficient to hold an intermediate substrate inplace without the use of adhesive and elastomerically biases the dieagainst the cover plate of the test fixture.

[0010] In U.S. Pat. No. 5,336,649, a precured RTV silicone strip, “gelpack”, is used for temporarily securing the die in place within apackage body. The RTV silicone strip exhibits a static charge andcoefficient of friction sufficient to hold the die in place within aburn-in carrier. Another embodiment discloses the use of a tape type dieattach adhesive, known under the trademark of E.I. duPont de Nemours ofWilmington, Del. as Kapton QL Die Attach Adhesive, to hold the die inplace during burn-in. The adhesive is heated, but for a shorter timethan for a permanently packaged die. This allows a standard processsetup to be used for temporary die attachment while permitting theadhesive attachment of the die to be readily overcome subsequent totesting and burn-in. Also disclosed is the use of water soluble hot meltglass, a thermoplastic material, to temporarily hold the die duringtesting and burn-in. After testing, the hot melt glass is removed bydissolving it using deionized water, thereby freeing the die from thepackage. In yet another instance, the die may be adhesively bonded tothe carrier through the use of a sugar and water solution. Aftertesting, the package including the die is placed in deionized water,which causes the sugar to dissolve, thereby freeing the die from thepackage.

[0011] However, these prior types of die attachment techniques haveinherent problems. They either require specific types of mechanicalmounting arrangements to be designed into the burn-in carrier, orrequire that the silicone “gel pack” exhibit sufficient electrostaticcharge to retain the die in the burn-in carrier, or require the carefulspraying of the adhesive in the burn-in carrier to minimize overspray ofthe adhesive, or require the use of a water cleaning solution aftertesting and burn-in to remove the adhesive remnants.

SUMMARY OF THE INVENTION

[0012] The present invention is directed to a method of using adhesivetape to temporarily retain a die being temporarily held in a fixtureduring testing and burn-in. The method of the present invention uses adie cut piece of adhesively coated tape to hold a die in a test andburn-in fixture. Upon subsequent heating of the tape beyond the normaloperating range of the adhesive coating on the tape, the die is removedfrom the tape, the tape is removed from the test and burn-in fixture,and the remaining adhesive, if any, is removed from the test and burn-infixture.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0013] The present invention will be better understood when the drawingsare taken in conjunction with the description of the invention wherein:

[0014]FIG. 1 is a top view of a substrate on which a softbond wirebondconnection has been made during the method of the present invention;

[0015]FIG. 2 is a partial cross sectional view of the substrate shown indrawing FIG. 1;

[0016]FIG. 3 is a flow diagram of the present invention; and

[0017]FIG. 4 is a sectional view of the die cutting the adhesivelycoated tape of the present invention and the vacuum transfer apparatuswhich may be used in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0018] Referring to drawing FIGS. 1 and 2, a testing and burn-in fixture10 includes a package body 12 and a cover plate 14. The package body 12includes a die receiving cavity 16 in which a die 2 is retained. The diereceiving cavity 16 has any desired size and shape which is necessary toaccommodate the die 2 to act as a carrier for the testing and burn-in ofthe die 2. A plurality of external connector leads (also referred to as“connectors”) 18 extends from the testing and burn-in fixture 10 toconnect the die 2 to external testing and burn-in circuitry. In thisinstance, the external connectors 18 are attached to the package body,extend therefrom, and are shown as connector pins 18, which are used ina dual in-line package or quad flat pack configuration. The externalconnectors 18 terminate in contact pads 20 in the package body 12 whichare generally in line with the bond pads 22 of the die 2. The bond pads22 of the die 2 are connected to the contact pads 20 of the package body12 by lead wires 24 to allow testing of the die 2.

[0019] Referring to drawing FIG. 2, the testing and burn-in fixture 10is shown in a partial cross sectional view. As shown, the testing andburn-in fixture may include one or more holes 26 located in the bottomof the package body 12 to use in the removal of the die 2 therefrom.Also shown, a piece of adhesively coated tape 30 is located between thedie 2 and the bottom of the package body 12 to retain the die 2 duringthe testing and burn-in of the die 2.

[0020] Any suitable type of high temperature, pressure sensitive,adhesively coated tape 30 may be used to retain the die 2 in the packagebody 12 during the testing and burn-in thereof. The adhesively coatedtape 30 may be coated with adhesive on either a single side or on bothsides, as desired. The tape 30 is cut to such size and shape as isnecessary to fit within the package body 12 to retain the die 2 thereinduring testing and burn-in. It is not necessary that the adhesive tape30 be cut to the size of the die 2 being held in the fixture 10 duringtesting and burn-in thereof. While any suitable high temperature,pressure sensitive adhesive tape 30 may be used, it is preferred thatthe tape 30 have an adhesive thereon with a maximum working temperatureof approximately 180 degrees Centigrade. Also, the tape 30 may usediffering types of suitable adhesives thereon, such as pressuresensitive silicone adhesive, acrylic adhesive, etc. It is also desirablefor the adhesive on the tape 30 to leave a non-conductive ash when itoxidizes or burns to prevent any potential problems of electricalconnections with any portion of any die 2 being tested or duringburn-in. In situations where the die 2 does not need to be tested orsubjected to burn-in temperatures of up to and including approximately180 degrees Centigrade and where a lower testing and burn-in temperatureis acceptable, an adhesive such as an acrylic adhesive which is suitableup to approximately 155 degrees Centigrade may be used. Also, for easeof processing, it is desirable that tape 30 be backed tape, such asthrough the use of paper or the like, so that the piece of the tape 30to be used in the fixture 10 may be easily, readily cut by a suitablecutting die having the desired configuration without the cutting diecutting through the paper backing on the tape. In this manner, the pieceof tape 30 used in the fixture 10 may be readily removed after cuttingto size by a simple vacuum tool, such as a pick and place TEFLON® nosevacuum tool.

[0021] The preferred tape 30 for use in the present invention isTEMP-R-TAPE of Kapton, the Kapton family K 100, K 102, K 103, K 104, K250, K 250X and K 350 as sold by CHR Industries, Inc. of New Haven,Conn. Such preferred type tape has an adhesive thickness which variesfrom 0.0015 inches to 0.0045 inches, a backing thickness of 0.0005inches to 0.002 inches, and a maximum adhesive working temperature rangefrom 150 degrees Centigrade to 180 degrees Centigrade.

[0022] Referring to drawing FIG. 3, the method of the present inventionis shown. As previously stated and shown, a bare die 2 is attached to atest and burn-in fixture 10 by a high temperature, pressure sensitiveadhesive tape 30. The electrical connections between the die 2 and thefixture 10 are made by solftool bonding, as shown in drawing FIGS. 1 and2, or may be made by a bump contact method, if desired. The adhesivetape 30 holds the die 2 securely during all processing of the die 2until such time as it is desired to remove the die 2 from the fixture10. After the desired processing, the die 2 is removed from the carrierby subjecting the carrier to a thermal profile which degrades theadhesive on the tape 30 to a point where the die 2 can be picked out ofthe carrier with minimal force. At that time, any remaining adhesive onthe fixture 10 may be removed by heating the fixture 10 until theremaining adhesive is ashed and can be removed from the fixture by anysuitable desired method, such as by a blast of compressed air, or thelike, by chemical solvent cleaning, or by mechanical cleaning.

[0023] As shown, in the step 100 of the method of the present invention,a test/burn-in fixture 10 suitable for use with the die 2 to be testedis provided. A cutting die is used to cut the desired piece of hightemperature, pressure sensitive tape 30 to size to fit into thetest/burn-in fixture 10 as step 200. The cut piece of tape 30 istransferred in step 300 to the test/burn-in fixture 10 by any suitablemeans, such as through the use of a TEFLON® nose, pick and place toolwhich uses a vacuum to pick up the cut piece of tape 30 and place it inthe fixture 10. The die 2 is mounted on the adhesive coating of the tape30 in the test/burn-in fixture 10 as step 400 of the present invention.At this time, the bond pads 22 on the die 2 are connected to the contactpads 20 of the fixture 10 by suitable means as step 500 of the presentinvention. At step 600 of the present invention, the die 2 is tested andburned-in as desired in the fixture 10 in which the die 2 is retainedthrough the use of suitable adhesive tape 30. After testing and burn-inof the die 2, as step 700 of the present invention, the die 2 andfixture 10 are heated to a sufficient temperature to degrade theadhesive holding the die 2 on the tape 30 to allow the removal of thedie 2 from the tape 30. As step 800 of the present invention, the die 2is removed from the fixture 10 after sufficient heating thereof todegrade the adhesive on the tape 30. Subsequent to the removal of thedie 2 from the fixture 10, as step 900 of the present invention, thetape 30 is removed from the fixture 10 and is disposed in a suitablemanner. At this time, the fixture 10 is cleaned, as step 1000 of thepresent invention, to remove any remaining adhesive from the fixture 10to allow the reuse thereof. The preferred method of cleaning anyremaining adhesive from the fixture 10 is to heat the fixture 10 to asufficient temperature to ash any remaining adhesive. Such a suitabletemperature for the preferred tape and adhesives as described herein isin the range of 260 to 300 degrees Centigrade to degrade the adhesive toallow the removal of the die 2 from the fixture 10 and ash any remainingadhesive of the fixture 10. At this time, the fixture 10 may be easilycleaned by any suitable method of any ash adhesive thereon for reuse.

[0024] Referring to drawing FIG. 4, tape 30 is shown having a suitablebacking 32, such as paper, being supported on a cutting surface 34. Acutting die 36 of the desired configuration is used to cut the tape tobe used in the fixture 10 to retain the die 2 therein during testing andburn-in. The cutting die 36 may be actuated by any suitable apparatus ormay comprise a cutting wheel, if desired. After cutting the tape 30 tothe desired configuration, a vacuum pick and place tool 38 having aTEFLON® nose 40 is used to transfer the piece of tape 30 to the fixture10. The vacuum pick and place tool may be of any suitable design andactuation for use in placing the piece of tape 30 in the fixture 10.

[0025] From the foregoing it can be seen that many changes, additions,deletions, etc. may be made to the present invention which fall withinthe scope thereof. Such are that different types of tape havingdiffering types of adhesives may be used. Different types of cleaning ofthe fixture 10 may be used to remove any adhesive remaining thereon. Thetape 30 may be placed in the fixture 10 by various suitable means, otherthan using a vacuum, to transfer the tape 30. The fixture 10 may be ofany suitable type to retain the die 2 during testing and burn-in. Thedie 2 may be connected to the fixture 10 by any suitable means such aswire bonding or tape automated bonding.

What is claimed is:
 1. A semiconductor die and a retaining fixture usedduring burn-in operations for said semiconductor die, said assemblycomprising: a semiconductor die having a first side having at least onebond pad thereon and a second side; a fixture having a cavity having abottom surface for temporarily retaining said semiconductor die thereinduring said burn-in operations, said fixture including at least onecontact pad located on a surface of said fixture other than said bottomsurface for connection to the at least one bond pad on saidsemiconductor die, said bottom surface having a hole extendingtherethrough for use in removal of said semiconductor die from saidfixture; a piece of tape having an adhesive coating on each side thereoffor temporarily retaining said semiconductor die in the cavity in saidfixture, the piece of tape located in the cavity in said fixture, thepiece of tape temporarily secured to the second side of thesemiconductor die and temporarily secured to the bottom surface of thecavity of said fixture covering the at least one hole extending throughthe bottom surface of the cavity of said fixture; and at least one leadwire directly connecting the at least one bond pad of said semiconductordie to the at least one contact pad of said fixture.
 2. The assembly ofclaim 1, wherein the piece of tape is substantially the size of thecavity in said fixture.
 3. The assembly of claim 1, wherein the piece oftape is substantially the size and shape of the cavity in said fixture.4. The assembly of claim 1, wherein the adhesive coating on the piece oftape comprises a silicone polymer type adhesive.
 5. The assembly ofclaim 1, wherein the adhesive coating on the piece of tape comprises anacrylic type adhesive.